EAL

CKD: Dietary Fat Requirements (2010)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

Determine if a hypocaloric diet was effective in reducing body mass index (BMI) and if folate and vitamin B₆ supplementation reduced homocysteine levels in obese renal transplant patients with hyperhomocysteinuria.

Inclusion Criteria:

All clinic patients with both a BMI of 30 and hyperhomocysteinuria (definition not given) at one year after transplant.

Exclusion Criteria:

Not meeting inclusion criteria.

Description of Study Protocol:

Recruitment: All clinic patients meeting criteria

Design: Longitudinal; all patients given dietary counseling

Intervention: Hypocaloric (≤30 kcal per kilogram per day) and hypolipidemic (not defined) diet. All patients were given five mg per day of folic acid and 50 mg per day of vitamin B₆. All patients received cyclosporin A and mycophenolate mofetil for immunosuppression.

Statistical Analysis: Two-way ANOVA for data given in results.

Data Collection Summary:

Timing of Measurements

Baseline data were collected at one year after transplantation. Intervention data was collected for up to two years. Only two years (one year of intervention) was given in results.

Dependent Variables

BMI
Homocysteine
Proteinuria
Creatinine clearance
Blood pressure
Serum lipids and lipoproteins.

Independent Variables

Hypocaloric (>30 kcal/kg/day) and hypolipidemic (not defined) diet plus five mg per day of folic acid and 50 mg per day of vitamin B₆.

Control Variables

None.

Description of Actual Data Sample:

Initial N: 118 (55 males, 63 females)

Attrition (final N): 118

Age: Range, 22 years to 78 years

Ethnicity: Not given, but study done in Eastern Europe

Other relevant demographics: All one year post-transplantation at start of intervention

Location: Prague, Czech Republic.

Summary of Results:

Variables	Baseline Measures and Confidence Intervals Mean±SD	One-year Intervention Measures and Confidence Intervals Mean±SD	Statistical Significance of Difference P
BMI (kg/m²)	35.5±3.2	27.4±2.8	<0.025
Total Homocysteine (µmol/L)	35.2±12.4	12.7±2.9	<0.001
Folate (nmol/L)	17.8±8.5	32.9±9.	<0.01
Vitamin B₆ (mcg/L)	5.4±1.5	9.3±2.2	<0.01
LDL Cholesterol (mmol/L)	4.1±1.2	3.0±0.7	<0.01
Triglycerides (mmol/L)	3.8±1.6	2.6±0.6	<0.01
Leptin (ng/L)	48.3±20.7	16.8±8.0	<0.001
Creatinine Clearance (ml/s)	1.0±0.5	0.9±0.4	NS
Mean Blood Pressure	135/85	130/85	NS

Other findings: No significant change in HDL cholesterol, lipoprotein A, Apo E isoforms, proteinuria or cyclosporin level.

Author Conclusion:

Dietary intervention can reduce BMI and homocysteine levels in obese, hyperhomocyteinuric renal transplant patients.

Funding Source:

Government:

Internal Grant Agency of the Czech Republic

Reviewer Comments:

No data given by age, sex, initial BMI or homocysteine levels.

Quality Criteria Checklist: Primary Research
Relevance Questions
	1.	Would implementing the studied intervention or procedure (if found successful) result in improved outcomes for the patients/clients/population group? (Not Applicable for some epidemiological studies)	Yes
	2.	Did the authors study an outcome (dependent variable) or topic that the patients/clients/population group would care about?	Yes
	3.	Is the focus of the intervention or procedure (independent variable) or topic of study a common issue of concern to dieteticspractice?	Yes
	4.	Is the intervention or procedure feasible? (NA for some epidemiological studies)	Yes

Validity Questions
1.	Was the research question clearly stated?		Yes
	1.1.	Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified?	Yes
	1.2.	Was (were) the outcome(s) [dependent variable(s)] clearly indicated?	Yes
	1.3.	Were the target population and setting specified?	Yes
2.	Was the selection of study subjects/patients free from bias?		N/A
	2.1.	Were inclusion/exclusion criteria specified (e.g., risk, point in disease progression, diagnostic or prognosis criteria), and with sufficient detail and without omitting criteria critical to the study?	Yes
	2.2.	Were criteria applied equally to all study groups?	N/A
	2.3.	Were health, demographics, and other characteristics of subjects described?	Yes
	2.4.	Were the subjects/patients a representative sample of the relevant population?	Yes
3.	Were study groups comparable?		N/A
	3.1.	Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT)	N/A
	3.2.	Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline?	N/A
	3.3.	Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.)	N/A
	3.4.	If cohort study or cross-sectional study, were groups comparable on important confounding factors and/or were preexisting differences accounted for by using appropriate adjustments in statistical analysis?	N/A
	3.5.	If case control study, were potential confounding factors comparable for cases and controls? (If case series or trial with subjects serving as own control, this criterion is not applicable.)	N/A
	3.6.	If diagnostic test, was there an independent blind comparison with an appropriate reference standard (e.g., "gold standard")?	N/A
4.	Was method of handling withdrawals described?		N/A
	4.1.	Were follow-up methods described and the same for all groups?	N/A
	4.2.	Was the number, characteristics of withdrawals (i.e., dropouts, lost to follow up, attrition rate) and/or response rate (cross-sectional studies) described for each group? (Follow up goal for a strong study is 80%.)	N/A
	4.3.	Were all enrolled subjects/patients (in the original sample) accounted for?	Yes
	4.4.	Were reasons for withdrawals similar across groups?	N/A
	4.5.	If diagnostic test, was decision to perform reference test not dependent on results of test under study?	N/A
5.	Was blinding used to prevent introduction of bias?		N/A
	5.1.	In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate?	No
	5.2.	Were data collectors blinded for outcomes assessment? (If outcome is measured using an objective test, such as a lab value, this criterion is assumed to be met.)	Yes
	5.3.	In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded?	N/A
	5.4.	In case control study, was case definition explicit and case ascertainment not influenced by exposure status?	N/A
	5.5.	In diagnostic study, were test results blinded to patient history and other test results?	N/A
6.	Were intervention/therapeutic regimens/exposure factor or procedure and any comparison(s) described in detail? Were interveningfactors described?		Yes
	6.1.	In RCT or other intervention trial, were protocols described for all regimens studied?	Yes
	6.2.	In observational study, were interventions, study settings, and clinicians/provider described?	N/A
	6.3.	Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect?	Yes
	6.4.	Was the amount of exposure and, if relevant, subject/patient compliance measured?	Yes
	6.5.	Were co-interventions (e.g., ancillary treatments, other therapies) described?	Yes
	6.6.	Were extra or unplanned treatments described?	N/A
	6.7.	Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups?	N/A
	6.8.	In diagnostic study, were details of test administration and replication sufficient?	N/A
7.	Were outcomes clearly defined and the measurements valid and reliable?		Yes
	7.1.	Were primary and secondary endpoints described and relevant to the question?	Yes
	7.2.	Were nutrition measures appropriate to question and outcomes of concern?	Yes
	7.3.	Was the period of follow-up long enough for important outcome(s) to occur?	Yes
	7.4.	Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures?	Yes
	7.5.	Was the measurement of effect at an appropriate level of precision?	Yes
	7.6.	Were other factors accounted for (measured) that could affect outcomes?	???
	7.7.	Were the measurements conducted consistently across groups?	Yes
8.	Was the statistical analysis appropriate for the study design and type of outcome indicators?		Yes
	8.1.	Were statistical analyses adequately described and the results reported appropriately?	Yes
	8.2.	Were correct statistical tests used and assumptions of test not violated?	Yes
	8.3.	Were statistics reported with levels of significance and/or confidence intervals?	Yes
	8.4.	Was "intent to treat" analysis of outcomes done (and as appropriate, was there an analysis of outcomes for those maximally exposed or a dose-response analysis)?	N/A
	8.5.	Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)?	???
	8.6.	Was clinical significance as well as statistical significance reported?	Yes
	8.7.	If negative findings, was a power calculation reported to address type 2 error?	N/A
9.	Are conclusions supported by results with biases and limitations taken into consideration?		Yes
	9.1.	Is there a discussion of findings?	Yes
	9.2.	Are biases and study limitations identified and discussed?	???
10.	Is bias due to study's funding or sponsorship unlikely?		Yes
	10.1.	Were sources of funding and investigators' affiliations described?	Yes
	10.2.	Was the study free from apparent conflict of interest?	Yes